49 / INPUT
Pressure from Velocity
The problem
Without a pressure sensor, strokes stay the same width whether you draw slowly or quickly, so ink never feels physical.
The solution
Derived pressure from velocity thins fast strokes and thickens slow ones; hardware pressure is shown separately when available.
This mechanic is best experienced with a pointer.
Experiment
Task: Draw slowly, then quickly, and compare stroke width on both surfaces.
NAIVE
Draw slowly, then quickly
THOUGHTFUL
Draw slowly, then quickly
speed0 px/s
pressure0
Play with the values
0.55
0.45
0.35
0.15
0.95
How it works
Seen in
Drawing apps
Mouse and trackpad strokes still feel pressure-sensitive when velocity stands in for force.
Note apps
Handwriting weight varies with pace even without a stylus pressure channel.
Signature pads
Fast flourishes thin out while deliberate strokes stay heavier.
Whiteboards
Freehand marks respond to motion when hardware pressure is absent.